Flow guiding device and turbo-engine with at least one flow guiding device

ABSTRACT

A flow guiding device in a turbomachine with at least one rotor module that is arranged on a shaft is provided. The rotor module has at least two rotor discs between which respectively one rotor cavity is arranged. The rotor cavities are connected to each other in an air-guiding manner for an airflow by means of openings inside the rotor discs and at least one pressure sink device for creating a localized negative pressure is arranged inside the last rotor cavity as viewed in the main flow direction of the turbomachine.

REFERENCE TO RELATED APPLICATION

This application claims priority to German Patent Application No. 10 2015 219 022.6 filed on Oct. 1, 2015, the entirety of which is incorporated by reference herein.

BACKGROUND

The invention relates to a flow guiding device and a turbomachine.

In turbomachines, rotor modules, such as compressor or turbine modules, are used that have respectively one row of rotor discs. Rotor blades that project into the air channel are arranged at the rotor discs at the radially outer edge in order to supply energy to the air that is flowing inside the air channel in a compressor module, or to extract energy from the air that is flowing inside the air channel in a turbine module.

Radially below the rotor blades, the rotor discs are coupled to a shaft in the interior of the turbomachine, via which the rotor discs are driven. Here, it is known for example from WO 2014/133659 A1 or US 2007/0189890 A1 to let an airflow flow through the intermediate spaces between the rotor discs below the rotor blades, the so-called rotor cavities. This is done for the purpose of achieving a thermal impact on the rotor discs, among other reasons.

SUMMARY

There is the objective to create a maximally efficient flow control inside the rotor cavities, so that an efficient cooling is facilitated, for example.

The objective is achieved through a flow guiding device with features as described herein.

Openings are arranged inside the rotor cavities between at least two rotor discs, so that the rotor cavities are connected to each other in an air-conducting manner for an airflow. At least one pressure sink device for creating a localized negative pressure is arranged inside the last rotor cavity as viewed in the main flow direction of the turbomachine. In this manner, the airflow that is entering the rotor cavities can advantageously be guided through the openings in the direction of the at least one pressure sink device.

Due to the targeted creation of a localized negative pressure inside the last rotor cavity as well as to the openings inside the rotor discs, a pressure gradient can be created throughout the rotor cavities. The airflow passes the rotor cavities from front to back and can then be used in other parts of the turbomachine, if required.

The rotor module is advantageously configured as a compressor module, and the airflow can be guided through at least one inlet opening from the flow channel of the compressor module into at least one rotor cavity.

In a further embodiment, the rotor discs respectively have at least two openings that are arranged in an axisymmetric manner with respect to the shaft of the turbomachine. Through the axisymmetric arrangement, the rotation of the rotor discs is rendered as imbalance-free as possible.

Since the openings inside the rotor discs represent a material weakening of the rotor disc, the rotor discs respectively have a material reinforcement in the area of the openings in one embodiment. This material reinforcement can be configured as a ring and/or a web that surrounds the openings, for example.

In a further embodiment, the pressure sink device has at least one vortex rectifier and/or a means for creating a localized negative pressure through a targeted acceleration of the airflow. Inside the vortex rectifiers, a relative negative pressure is created due to the manipulation of the vortexes inside the rotor cavities.

The airflow can be guided from the pressure sink device into another part of the turbomachine, in particular to a turbine module. In this way, comparatively cool air can be used for cooling, for example.

In one embodiment, the turbomachine is configured as an aircraft engine.

The objective is also achieved by a turbomachine, in particular an aircraft engine, as described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in connection with the exemplary embodiments that are shown in the Figures.

FIG. 1 shows a schematic rendering of an axial compressor with an embodiment of a flow guiding device in a two-part aircraft engine.

FIG. 2 shows an enlarged rendering of the rotor cavities and the flow guiding device in a compressor module of the embodiment that is shown in FIG. 1.

FIGS. 3A, B, C show three embodiments for a rotor disc.

DETAILED DESCRIPTION

FIG. 1 shows an embodiment of a flow guiding device in connection with a rotor module of a turbomachine, namely an aircraft engine 100. The rotor module has a two-part axial compressor with two compressor modules 101, 101′. For reasons of clarity, the flow guiding device is shown only in connection with the first compressor module 101.

Air flows through the aircraft engine 100 in a main flow direction A, which is arranged in parallel to the shaft 103 of the aircraft engine 100. In the first compressor module 101, six stages are [arranged], respectively comprising a stator and a rotor (indicated in black in FIG. 1). Here, the rotors have rotor blades 105 that project into a compressor channel 106. The rotor blades 105 are arranged at the radial end of the rotor discs 1, 2, 3, 4, 5. At that, the rotor discs 1, 2, 3, 4, 5 are respectively connected to a shaft 103 of the aircraft engine 100.

Four rotor cavities 11, 12, 13, 14 are located radially below the rotor blades 105 and between the rotor discs 1, 2, 3, 4. The last rotor cavity 15 is arranged behind the fourth rotor disc 4. Together, the rotor cavities occupy a relatively large space around the shaft 103, with a stream of air L flowing therethrough. Through an inlet opening 102, the stream of air L enters the space of the rotor cavities 11, 12, 13, 14, 15 from a compressor stage. At that, the air has the pressure, density and temperature that is present at the inlet opening 102.

In order to facilitate an enhanced flow through the individual rotor cavities 11, 12, 13, 14, 15, the rotor discs 1, 2, 3, 4, 5 respectively have openings 21, 23, 23, 24, 25 through which the stream of air L can flow to the rear in the axial direction and through the rotor discs 1, 2, 3, 4. For reasons of clarity, only one opening 21, 22, 23, 24, 25 is respectively shown in FIG. 1.

In FIG. 2, the rotor cavities 11, 12, 13, 14, 15 and the guiding of the flow are shown in detail.

In order to provide for an efficient flow through the rotor cavities 11, 12, 13, 14, 15 in the axial direction, a pressure sink device 30 is arranged inside the last rotor cavity 15 as viewed in the main flow direction A. In a manner that will be described below, the sink device 30 creates a localized negative pressure inside the last rotor cavity 15. This negative pressure leads to a pressure gradient being superimposed on the complex flow field inside the rotor cavities 11, 12, 13, 14, 15, thus providing for a total flow from the inlet opening 102 to the pressure sink device 30. What is thus present is a stream of air L that extends through all rotor cavities 11, 12, 13, 14, 15, wherein the stream can flow through the openings 21, 22, 23, 24, 25 inside the rotor discs 1, 2, 3, 4, 5. The flow conditions are complex in each rotor cavity 11, 12, 13, 14, 15, as radial portions of the flow are also superimposed on this axial flow due to the rotation of the shaft and the rotor discs 1, 2, 3, 4, 5.

Thus, the flow guiding device has rotor discs 1, 2, 3, 4, 5 with openings 21, 22, 23, 24, 25 for an air-guiding connection of the rotor cavities 11, 12, 13, 14, 15 to each other, wherein this stream of air L is caused by the potential that is generated by the pressure sink device 30 inside the last rotor cavity 15 (i.e., the localized negative pressure).

The combination of these means facilitates an improved air exchange and an enhanced flushing effect in the rotor cavities 11, 12, 13, 14, 15 in the axial direction, which facilitates a better thermal management of the aircraft engine 100. In this way, the rotor gaps, i.e., the gap between the rotor blade tips and the surrounding housing, can be minimized.

During operation, the rotor discs 1, 2, 3, 4, 5 sometimes rotate at very high velocities, so that complex flow patterns of the stream of air L occur inside the rotor cavities 11, 12, 13, 14, 15 due to the radial acceleration. Since a pressure sink device 30 is arranged inside the axially last rotor cavity 15, an axial flow is superimposed on this flow pattern.

In the present case, the pressure sink device 30 is configured as a vortex rectifier (also referred to as a vortex reducer). At that, the vortex rectifier 30 comprises a straight pipe that is aligned in the radial direction and inside of which the radial flow is guided within the last rotor cavity 15. A pressure gradient is present in the radial direction inwards across the length of the vortex rectifier 30, i.e., air is suctioned from the rotor cavities 11, 12, 13, 14, 15 in the direction of the hub. The vortex rectifiers 30 have an impact on the formation of the vortexes inside the rotor cavities 11, 12, 13, 14, 15, wherein particularly the absence of an axial symmetry plays a role here. In alternative embodiments, also other non-axisymmetric means can serve as a pressure sink device 30, such as for example deflector plates (paddles) at the bottom end of the rotor cavities 11, 12, 13, 14, 15 or flanges (screw heads). The same effect may also be achieved by the targeted use of rough surfaces (for example through radially extending milling marks, through locally applied radial strips on blades in the kind of transition strips, created by means of injection methods) for increasing the thickness of the flow edge area. In this way, the low pressure inside the rotor cavities 11, 12, 13, 14, 15 can be imprinted in a targeted manner, which leads to an improved air circulation in the rotor cavities 11, 12, 13, 14, 15.

FIGS. 3A, 3B and 3C show three embodiments of a rotor disc 1 in top view, in which three openings 21 are arranged so as to be respectively offset by 120°. Since the openings 21 principally represent a material weakening in the rotor disc 1, it may be expedient to specifically reinforce these areas.

FIG. 3A shows an embodiment in which the material is configured to be slightly stronger in the form of a material reinforcement 40 in the area directly surrounding the openings 21. In FIG. 3B, the material reinforcement 40 is realized in the form of radially arranged ribs.

In FIG. 3C, the material reinforcement 40 is configured in a ring-shaped manner in order to compensate for the increasingly occurring circumferential stresses.

Incidentally, the flow guiding devices of the kind as they are described herein can also be used in connection with turbine modules, either in addition or as an alternative.

Also, the embodiments of the flow guiding devices have been described in connection with an aircraft engine. Principally it is also possible to use the flow guiding device in a different turbomachine, for example a stationary gas turbine.

PARTS LIST

-   1 first rotor disc -   2 second rotor disc -   3 third rotor disc -   4 fourth rotor disc -   5 fifth rotor disc -   11 first rotor cavity -   12 second rotor cavity -   13 third rotor cavity -   14 fourth rotor cavity -   15 last rotor cavity -   21 first opening -   22 second opening -   23 third opening -   24 fourth opening -   25 fifth opening -   30 pressure sink device -   31 device for deflecting a radial flow -   40 material reinforcement -   100 turbomachine -   101 compressor module -   102 inlet opening -   103 shaft -   104 turbine module -   A main flow device -   L stream of air in rotor cavities 

1. A flow guiding device in a turbomachine with at least one rotor module, which is arranged on a shaft, wherein the rotor module has at least two rotor discs between which respectively one rotor cavity is arranged, wherein the rotor cavities are connected to each other in an air-guiding manner for an airflow by means of openings inside the rotor discs, and in that at least one pressure sink device for creating a localized negative pressure is arranged inside the last rotor cavity as viewed in the main flow direction of the turbomachine.
 2. The flow guiding device according to claim 1, wherein the airflow that enters the rotor cavities can be guided through the openings in the direction of the at least one pressure sink device.
 3. The flow guiding device according to claim 1, wherein the rotor module is configured as a compressor module, and wherein the airflow can be guided from the flow channel of the compressor module into at least one rotor cavity through at least one inlet opening.
 4. The flow guiding device according to claim 1, wherein the rotor discs have respectively at least two openings that are arranged in an axisymmetric manner with respect to the shaft of the turbomachine.
 5. The flow guiding device according to claim 1, wherein the rotor discs respectively have a material reinforcement in the area of the openings.
 6. The flow guiding device according to claim 5, wherein the material reinforcement is configured as a ring and/or a web that surrounds the openings.
 7. The flow guiding device according to claim 1, wherein the pressure sink device at least has vortex rectifiers and/or a means for creating a localized negative pressure by means of a targeted acceleration of the airflow.
 8. The flow guiding device according to claim 1, wherein the airflow can be guided from the pressure sink device into another part of the turbomachine, in particular a turbine module.
 9. The flow guiding device according to claim 1, wherein in at least one rotor cavity a device for deflecting a radial stream of air inside the at least one rotor cavity is arranged, wherein the deflected air can be guided axially in the direction of the pressure sink device.
 10. The flow guiding device according to claim 1, wherein the turbomachine is configured as an aircraft engine.
 11. A turbomachine, in particular an aircraft engine, with at least one flow guiding device according to claim
 1. 